This invention relates to hot pelletizers for extruders wherein there is provided a cutting rotor rotating in front of the dies serving to extrude the plastic ribbons, and a colling device for spraying the cutting rotor with a cooling medium such as water.
Hot pelletizers are already known for the prevention of difficulties with hardened plastic elements when they tear or break while exiting out of dies and also for the prevention of adhesion between the pellets. In such pelletizers, a cutting rotor cuts the emerging plastic ribbons before they are solidified, on the one hand, and when they have, on the other hand, sufficiently emerged for the desired pellet size. In order to prevent the sticking together of the pellets it is necessary to cool them immediately after separation which is done by spraying the cutting rotor with a colling fluid.
The heretofore known hot pelletizers are furnished with rotating knives whereby single knives may be arranged so that they may be easily exchanged when damaged or may be reground when needed. These devices are extremely difficult to handle in regard to the setting and adjustment of the cutting knives in addition to the danger brought about by the conventional method of spraying that individual pellets, which are still soft, adhere and agglomerate, thereby making the pellitizer and the consecutive drying devices inoperable. Furthermore, it has been found in practical experience that even intensive spray-cooling does not prevent pellets from sticking together at the bottom. Increased cooling, on the other hand, causes the danger of slowly plugging-up of the die.